–10:28 p.m. update: Revised to reflect the point that Marecic himself chose not to sign with the 49ers this week, according to a source.

When does Jim Harbaugh ever volunteer specific information about acquiring a new player?

Just about never. Harbaugh almost never does, not intentionally.

So it was interesting Monday when Harbaugh gave a detailed answer about replacing fullback Bruce Miller, out with a broken scapula.

“We’re bringing in Owen Marecic, hopefully in route, and we’ll look at our options,” Harbaugh said of his former Stanford fullback/linebacker.

And then… the 49ers didn’t bring in Marecic and instead examined other fullback avenues.

What happened here?

Here’s what: Though far from a franchise-turning moment, these machinations partly illuminated the creative tension that fuels Harbaugh’s relationship with general manager Trent Baalke.

Harbaugh wanted Marecic, surely with the knowledge that Baalke and the personnel department had reservations in the past.

Though a source stressed that Baalke was on board with the signing this week and that Marecic himself chose not to come to the 49ers this week, it was an interesting time for Harbaugh to volunteer a name.

Baalke didn’t want him, and it all played out in front of us, if you were watching carefully.

There is a back story, there are discussions, and relationships can evolve. And tension between a strong coach and confident executive, by the way, is not necessarily a bad thing at all.
Sometimes it’s the best way for two leaders to co-exist–the New York Giants won Super Bowls with Bill Parcells and George Young alternately clashing and embracing.

Bill Walsh had his moments with Eddie DeBartolo, Jr., and John McVay, and that all turned out relatively well.

So it was notable that Harbaugh offered Marecic’s name so easily not long after Marecic’s brief, inactive stint with the team this season.

Important point: Harbaugh doesn’t have control over who gets signed–he has a great deal of influence, but he’s not in charge of the 49ers’ roster.

That contracted power belongs to Baalke, and it’s the way CEO Jed York wants it. (And Harbaugh, I’m told, never asked for it during the January 2011 negotiations to join the 49ers.)

So Harbaugh didn’t get his guy after floating the Marecic trial balloon.

And yes, when Harbaugh sits down with York to talk about a new contract this off-season, I would guess that he will ask for more input in such personnel matters.

No doubt, Baalke should and probably does seek Harbaugh’s opinion, mostly relating to the 49ers offense and especially the quarterback position.

Baalke and Harbaugh have agreed on many things since January 2011, and they have built this 49ers team into a model franchise that is bristling with talent.

But from what many sources have told me, there certainly have been disagreements, including over…

* Marecic, several times: Harbaugh wanted to draft him in 2011 and was not pleased when Baalke skipped him, taking, among others, Kendall Hunter nine picks ahead of Marecic in the fourth round.

* The third-string QB merry-go-’round this season: Harbaugh got a little manic going from Scott Tolzien to B.J. Daniels to Seneca Wallace to John Skelton to McLeod Bethel-Thompson…

Until the front office finally urged Harbaugh to settle it down. Bethel-Thompson is currently on the practice squad.

* Harbaugh has offered strong public suggestions that the 49ers should give new deals to several players, including safety Dashon
Goldson last season, that Baalke probably never planned to give.

On Monday, Harbaugh said the same about kicker Phil Dawson and safety Donte Whitner.

“Pay the man,” Harbaugh said of Dawson.

Gee, who was Harbaugh talking to?

* According to multiple sources, Baalke and York believed linebacker Aldon Smith would play sparingly when they agreed to keep him on the active roster for the Indianapolis game two days after his DUI arrest.

Then Smith played all 72 defensive snaps in the loss to the Colts before entering a rehab center a few days later.

* I would assume Baalke’s mis-fire 2012 draft, led by A.J. Jenkins and LaMichael James, comes up in conversations between Baalke and Harbaugh.

There’s an accumulation. But no, it’s not crisis time.

It’s just a natural development when you throw two alpha dogs into the same building for three years.

As someone who knows both men described it, their relationship has changed since 2011, but Harbaugh and Baalke still respect each other and believe they are good for each other and for the success of the 49ers.

Of course, when Harbaugh hears overtures from USC or Texas, he might start thinking about bargaining for more power along with more money.

But unless the 49ers win the Super Bowl and Harbaugh threatens to bolt immediately, I can’t see York giving Harbaugh control of the roster.

And even if the 49ers win the Super Bowl this February, remember, they’ll be doing it with the players Baalke acquired.

Harbaugh can’t win big without the talent Baalke has acquired, and Baalke’s talent won’t win without a superior coach.

There’s tension there, but there’s understanding and even some compromises, too. It’s just fascinating to watch it all go back and forth.